msm: kgsl: make cffdump work with the MMU enabled

The tools that process cff dumps expect a linear
memory region, but the start address of that region can
be configured. As long as there is only a single
pagetable (so that there aren't duplicate virtual
addresses in the dump), dumps captured with the
mmu on are easier to deal with than reconfiguring
to turn the mmu off.

Change-Id: If4070e60de50387dd12454b98e982b6713eeac42
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>